Lubricating oil composition



?atented Dec. 21, 1943 LUBRICATING on. coMrosrrmN Willard L. Finley,Edgewood Arsenal, Md., Milton Paul Kleinholz,

East

Chicago, Ind., and

Franklin M. Watkins, Chicago, Ill., asslgnors to Sinclair RefiningCompany, New York, N. Y., a corporation of Maine No Drawing. ApplicationDecember 19, 1941,

Serial No. 423,694

4 Claims.

This invention relates to improvements in compounded petroleumlubricating oils. The improved lubricating oil compositions of theinvention consist essentially of a petroleum oil base and an additionagent comprising a calcium salt of a dialkyl salicyclic acid amide,calcium diamyi salicylamide for example, the addition agent beingpresent in an amount insuifleient materially to alter the normallyliquid character of the petroleum lubricating oil itself, 0.5-5.0% onthe oil for example. Thesecompounds have the following structure:

'( E-O Oil-Nut):

where R is an aliphatic chain of three or more carbon atoms.

The trend of development in internal combustion engines has imposedincreasing burdens upon the oils used for their lubrication,particularly with respect to the operating temperatures and pressures.Extreme requirements in both of these respects are represented by theDiesel type of engine and supercharged aircraft engines. The usefuloperating life of a lubricating oil, in such severe services, isdetermined in a large measure by its thermal stability and by itsphysical capacity to continue functioning as a lubricant at the hightemperatures and pressures encountered.

One measure of thermal stability is resistance tocompounded, a highsolvent capacity for sludge of the character formed by oxidation ofpetroleum lubricating oils, and, perhaps of even greater-importance, theproperty of rendering deposits of sludge and "carbon" withinfthe enginesoft and friable rather than hard and coherent and of disintegrating andremoving such deposits as an incident of the normal operation of theengine. In engines of this type the high temperature to whichlubricating oil is subjected, particularly at the top of the stroke,frequently causes deposition of sludge and earbonization in the groovefor and behind one or more of the piston rings. Consequent sticking ofthe rings rapidly deprives, the piston and cylinder wall of properlubrication inducing excessive wear and, frequently, scoring of thecylinder wall. The formation of such "carbon deposits, hard enough andcoherent enough to involve sticking of the rings is materially retarded,if not avoided, by the use of the improved lubricating oil compositionsof my invention.

In the lubricating compositions of the present invention the calciumdialkyl salicylamides function not only to inhibit sludge formation andto modify the character of the carbon" deposits, but they also functionas strong anti-oxidants effective to reduce, at least over a prolongedinduction period, the rate of oxygen absorption at elevatedtemperatures, thus rendering such lubricating oil compositionsnon-corrosive, or less corrosive, to alloy bearing metals. Moreover,these addition agents are compatible with known film strength agentssuch as chlorinated diphenyL' brominated diphenyl, sulphurized spermoil, and the like. In lubricating oil blends including such filmstrength agents, the calcium dialkyl salicylamides inhibit thepro-oxidant effect that many of these film strength agents exert.

In applications of William L. Finley, Serial No. 368,992, filed December7, 1940, and Serial No. 407,002, filed August 15, 1941, respectively,lubricatingcompositions are disclosed which include as addition agentscalcium salts of normal and iso-alkyl esters of salicyciic acid.However, we have found that a lubricating composition including thecalcium salt of a dialkyl salicylic acid amide is in certain respectssuperior to a lubricating composition comprising the same base oil andthe calcium salt of an alkyl' ester of salicylic acid, particularly forservice under extreme temperature conditions. This superiorityapparently is due to the greater thermal stability of the calciumdialkyl salicylamides.

The greater thermal stability of the lubricating compositions of thepresent invention iswell illustrated by a comparison of two lubricatingcompositions compounded from the same base oil when heaetd at 500 F. for45 minutes. The base oil used for these comparative tests was a twicesolvent treated Pennsylvania bright stock having a viscosity ofapproximately 120 seconds at 210 F. Saybolt Universal. One of thelubricating compositions tested in this manner consisted of a sample ofthe base oil just d. scribed with 1% of calcium n-diamyl salicylamideincorporated therein. The other consisted of a sample of the same baseoil with 1% of calcium iso-octyl salicylate incorporated therein. Theheat treatment above described produced no visible precipitate in theoil containing calcium diamyl salicylamide whereas the oil containingthe calcium iso-octyl salicylate became cloudy due to precipitation ofdecomposition products. Both blends were allowed to cool and were thenfiltered. The composition containing calcium diamyl salicylamide wasfound to have retained all of its original calcium whereas thecomposition containing the calcium iso-octyl salicylate was found tohave retained only 26% of its original calcium content.

The oxidation inhibiting characteristics of the addition agents used inthe compositions of the present invention are strikingly illustrated bycomparison of the oxygen absorption rates of a blank base oil and of asample of the same base oil having 3.5% calcium n-diamyl salicylamideincorporated therein. The base oil, in this case a solvent treatedPemisylvania type base oil having a viscosity rating of S. A. E. 30,when subjected to the oxygen absorption test at 400 F., absorbed oxygenat a rate of 16.3 cc. per minute per 100 grams of oil. Under the sametest conditions the same base oil with 3.5% of calcium diamylsalicylamide incorporated therein absorbed oxygen at a rate of only 9.6cc. per minute per 100 grams of oil.

The sludge dispersing properties of the addition agents employed in thelubricating oil compositions of the present invention are illustrated bya comparison of the results of the Indiana sludging test applied tosamples of blank base oils and to samples of lubricating compositionscompounded from the same base oils in accordance with the presentinvention. Thus the Indiana sludging time of a 30 S. A. E. petroleumlubricating oil stock derived from a South Texas crude was increased bythe addition of 1.33% of calcium diamyl salicylamide from 12 hours forthe blank oil to 52 hours for the compounded oil. Similarly, the Indianasludging time for a 30 S. A. E. solvent-refined petroleum lubricatingoil stock derived 'from a Pennsylvania type crude.

was increased by the addition of 1.33% of calcium diamyl salicylamidefrom 200 for the blank oil to 330 for the compounded oil.

The addition agents employed in the lubricating oil compositions of ourinvention may be prepared by first reacting salicylic acid with thionylchloride in the presence of an aluminum chloride catalyst, therebyproducing salicylic acid chloride, then reacting the calicylic acidchloride with the selected dialkyl amine to produce the correspondingdialkyl salicylic acid amide, and thereafter preparing the calcium salteither by direct reaction of the dialkyl salicylic acid amide withcalcium hydroxide, preferably in admixture with at 30 in one instanceand in least a portion of the eventual base oil, or by first reactingthe dialkyl salicylic acid amide with sodium hydroxide in analcohol-benzene solution to form the sodium phenolate and thereafterreacting the sodium phenolate with calcium chloride to form the calciumsalt by double decomposition. The calcium dialkyl salicylic acid amidesare easily soluble in oil, even in highly solvent refined parafiin baseoils of high viscosity index, and they are more stable at hightemperatures than other known salicylic acid derivatives.

The following example will serve to illustrate the preparation of aspecific addition agent suitable for use in the lubircating oilcomposition of our invention. In this preparation 414 grams (3 mols) ofsalicylic acid were mixed with 848 grams (7.11 mols) of thionyl chlorideto provide a large excess of the latter. Aluminum chloride (0.75 gram)was added as a catalyst and the mixture was allowed to react at 40 F.for seven hours. Excess thionyl chloride was then removed bydistillation in a high vacuum so that the temperature did not exceed 50C. The salicylic acid chloride which remained as a residue in thisdistillation was then filtered to remove the catalyst and any unreactedsalicylic acid.

A-solution comprising 469.5 grams (3 mols) oi salicylic acid chlorideprepared as above described in 500 cc. of dry benzene was slowly addedto 950 grams (6 mols) of diamyl amine. The resulting mixture was cooledand rapidly stirred during addition of the benzene solution. After a.four hour reaction period an additional 500 cc. of benzene was added andthe benzene layer was carefully washed with a dilute hydrochloric acidsolution. Benzene was then removed by distillation and the diamylalicylic acid amide was thereafter distilled at 320-350 F. under apressure of 2 mm. of mercury.

A lubricating oil composition embodying our invention was prepared, fromthe diamyl salicylic acid amide obtained as above described, in thefollowing manner: A concentrate containing 12% of calcium diamylsalicylamide first was prepared by placing in a flask equipped with astirrer and an oil bath 352 grams of the base oil, a petroleumlubricating 011 stock having a viscosity rating of S. A. E. 30 derivedfrom a Pennsylvania type crude. Calcium hydroxide (12 grams or .162 mol)was added to the oil and suspended in the oil by rapid stirring whileheating the mixture to -190 F. 45 grams of the diamyl salicylic acidamide (.166 mol) and 2 grams of water were then added and the resultingmixture was stirred for 2 hours While continuing the heating. At the endof 2 hours the temperature of the mixture was increased to 280 F. toremove water and the mixture was then filtered to remove excess lime.-This concentrate was found to have a calcium content of 0.765% ascompared to a theoretical calcium content of 0.81%. The concentrate thusproduced finally was diluted with additional oil until the content ofcalcium diamyl salicylamide in the blend was. reduced to 1.33% by weighton the oil.

Two lubricating oil compositions embodying our invention were preparedby the above-described procedure from different base oils, the base oilcomprising a Pennsylvania type lubricating oil stock having a viscosityrating of S. A. E. the other a lubricating oil stock of approximatelythe same viscosity derived from a Mid-Continent type crude. In eachinstance the blend contained 1.33% of the addition agent. Conventionallaboratory tests, made on both of these lubricating compositions and onthe lubricating oil stocks from which they were prepared, are given inthe following table:

{ South Texas Pennsylvania ing a petroleum lubricating oil and as anaddition agent a calcium salt of a dialkyl salicylic Type of base oil1.33% 1.33% acid amide in which the alkyl groups contain at addm agentBlank 31 5 3 Blank 93 5 least 3 carbon atoms, the addition agent beingsalicylsalicylpresent in an amount sufiicient to improve the amideproperties of the petroleum lubricating oil effecting its use as alubricant but insuflicient mateggg S 35 35 2- 8 rially to alter thenormally liquid character of r re IIIIIII;IFII 450 435 500 490 thepetroleum lubricating oil.

$3. 2 253 2? 3 2 "32:2 2. A liquid lubricating oil composition com- PoB-lO 13-10 '5 0 15 prising a petroleum lubricating oil and calcium.iiiitfiffii: 132% Basic 1. 3% legit diamyl salicylamide; t calciumdiamyl g Nitrqgen --Pe cent amide being present in an amount sufficientto gffgfig gg' a' improve the properties of the petroleum lubri- 32geating oil effecting its use as a lubricant but insufvisositat'fi'liEs'II e312 e312 7812 72.0 ficient materially to alter thenormally liquid character of the petroleum lubricating oil.

Another sample of the diamyl salicylic acid ester prepared as abovedescribed was treated to form the sodium phenolate by reaction withsodium hydroxide in an alcohol-benzene solution. The calcium phenolatewas then formed by reacting the sodium phenolate with calcium chloride.The calcium diamyl salicylamide thus formed was obtained as a residue bydistilling off the benzene and alcohol. The final product was a reddishresinous solid which was easily soluble in substantial proportions evenin oils of high viscosity index. Upon analysis, the reddish resinoussolid was found to have a calcium content of Patent No. 2,537,580.

4.72%, a nitrogen content of 4.09% and a chlorine content of 0.37%.

We claim:

1. A liquid lubricating oil composition compris- 3. A liquid lubricatingoil composition comprising a petroleum lubricating oil containing about0.5-5.0% of a calcium salt of a dialkyl salicylic acid amide in whichthe alkyl groups contain at least 3 carbon atoms.

4. A liquid lubricating oil composition comprising a petroleumlubricating oil and as an addition agent about 0.5-5.0% calcium diamylsalicylamide.

WILLARD L. FINLEY. MILTON PAUL KLEINHOLZ. FRANKLIN M. WATKINS.

CERTIFICATE OF CORRECTION.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows Page 2,first column, line 7, for "heaetd' read -heated-; line 70, for"calicylic acid" resid -salicylic acid--; second column, line 11;, for"lubiroating" readlubricating-; page 5, first column, line 17, in thetable, third column thereof, for "0.1.5" read --.Ol 5--; and that thesaid Letters Patent should be read with this correction therein that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of March, A. D. 19th.

Leslie Frazer (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,537,580. December 21, 191 .5.

WILLARD L. FINLEY,.ET AL.

It is hereby certified that error appears in the printed. specificationof the above numbered patent requiring correction as follows Page 2,first column, line 7, for "heaetd" read -heated--- line 70, for"calicylic acid" 1 read -salicylic acid-; second column, line 114., for"lubircating" reed 1ubr.icating-- page}, first column, line 17, in thetable, third column thereof, for "0.15" read --.oL; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the rec- 0rd of the case in the Patent Office.

Signed and sealed this 28th day of March, A. D. 19%.

Leslie Frazer (Seal) Acting Commissioner of Patents.

